John Millman

Day five had already seen Serena Williams, Naomi Osaka and Stefanos Tsitsipas dealt shock defeats, and there looked to be another in store as Millman surged into an 8-4 lead in the final-set tie-break having been two sets to one down.

Recent history was also on the side of Millman, who defeated Federer in the 2018 US Open, while the 20-time grand slam champion went into Friday's encounter having lost his previous three five-set matches.

However, Federer somehow reeled off six successive points, a stunning forehand pass securing a 4-6 7-6 (7-2) 6-4 4-6 7-6 (10-8) win that marked his 100th at Melbourne Park and booked a last-16 clash with Marton Fucsovics.

The first set the tone for an uncharacteristically error-strewn performance from Federer.

He committed 14 unforced errors in the opener, and a double fault followed by a wayward forehand gifted Millman the early lead.

Millman faced the only break point of the second, but it was vintage Federer in the subsequent tie-break, the Swiss masterful in equal measure at the baseline and the net as he raced into a decisive 6-1 lead.

The third followed a markedly similar pattern with Federer finding no way through the Millman resistance. That was until the 10th game, when the Queenslander's composure cracked and he pushed long to seemingly give Federer control of the match.

But even as the errors crept into his game, Millman displayed a remarkable ability to trade blows with Federer in the longer exchanges and he brought up break point with a superb return before winning a tremendous rally that ended with the Swiss sending a forehand into the net.

Federer was 30-0 ahead in the subsequent game, only for four successive errors to allow Millman to hold, with a love hold then sending an absorbing contest to a fifth.

Another unforced error gave Millman the initiative in the decider and, though he gave the break back and squandered a pair of break points at 3-3, the home hope appeared on course to repeat his 2018 achievement in the tie-break.

Indeed, it was Millman who seemed to have the most left in the tank, and an astonishing cross-court pass put him within two points of victory.

Federer, though, is still capable of defying the odds at the age of 38, and he delivered a reminder that he should never be counted out with an emphatic response that capped an epic of four hours and three minutes in fitting fashion, his forehand passing shot making the most of an indecisive Millman volley.

Federer appeared destined for a third-round exit when he fell behind 8-4 in the decisive match tie-break at the end of the fifth set.

Millman had come from two sets to one down to move within two points of victory, but Federer rattled off six successive points to seal his 100th win at the Australian Open 4-6 7-6 (7-2) 6-4 4-6 7-6 (10-8) in four hours and three minutes.

The 20-time grand slam champion prevailed despite hitting 82 unforced errors, 48 of them coming off the forehand side.

Asked about that number in his post-match media conference, Federer replied: "I mean, honestly, nothing against the statistics people, but over a four-hour match you're going to hit unforced errors.

"What is an unforced error? Is it when it comes at 120 [kilometres] an hour or 135 or you're on the stretch? So, for me, he pushed me to go for more.

"You know me – I'm not going to hold back and just rally all the time. I will always try to make plays, and for that, I will miss some.

"Of course, sometimes I wish I could have maybe hit a few more winners instead of unforced errors, but, you know, it shows how slow the courts can be, as well, you know, how many rallies get created, how he didn't serve and volley once.

"I served and volleyed maybe what, 10 times? Five times? It's that crazy at these moments. When you can come in and you play serve and volley and, you know, volley errors don't count I don't think ever, and rally errors always count. So, there you go."

Federer was effusive in his praise for Millman, who defeated the Swiss at the 2018 US Open.

"I just think he's just so, so tough from the baseline. He's got sort of good speed on the backhand, on the forehand," added Federer when asked why Millman is such a tough opponent.

"The way he hits it makes it, for me, unsure if I should pull the trigger or I shouldn't. Is it there to be hit or not? Every time I get a ball, I'm in two ways, because I have the option to do that with my game, but then he covers the court very well.

"Because he hits it hard enough, maybe it's harder for me to find [an] angle. I think the biggest problem for me was just I wasn't able to get… I was not returning poorly, per se; I was just not getting into those neutral rallies, finding the ways to unlock him.

"That's his credit. He's a great player. He's got great attitude, and that's why I mumbled something to him at the net just saying, 'I have so much respect for you, and it's such a pity, I'm so sorry, but well played', and all that stuff, because I really feel that way for John."

Federer made serene progress into round three in Melbourne with a 6-1 6-4 6-1 defeat of Filip Krajinovic and will now face Millman, a 6-4 7-5 6-3 victor over Hubert Hurkacz.

Their only previous grand slam meeting came at the 2018 US Open when the Australian won a round of 16 encounter in four sets in blistering heat in New York.

Asked if that match had pushed him further than any other physically, he said: "Yeah, definitely. I don't know anything remotely close. I was just happy it was over.

"I never had that [before]. I rather go back in time [and think I'd like to] play that match again. But I don't have that feeling about that match. I was just happy the US Open was over and I could focus.

"I think it was a combination of many things that went wrong for me on that day, plus the opponent was ready and tough as nails.

"I have no regrets. I tried everything in the match itself, it was just not meant to be that day. I hit the wall."

Conditions in Melbourne have been much kinder for Federer so far, both meteorologically and in terms of the draw.

The third seed was barely tested by first-round opponent Steve Johnson or Krajinovic, but rubbished suggestions that would leave him undercooked.

"I prefer this much more than being overcooked," said the Swiss.

"I prefer it this way because you have always extra left in the tank if you need it."

Federer is likely to have to dig deeper against Millman, especially as he may be in the unusual position of not being the crowd favourite.

Millman has already suggested the match should be moved away from Rod Laver Arena due to the number of corporate fans that inhabit the main show court at Melbourne Park - a request that is likely to fall on deaf ears - but Federer is more than happy to play in a raucous atmosphere.

He said: "I'm always happy when the crowd gets involved.

"I don't choose which court I play on. I don't know if he was joking or if he was serious [about moving].

"You would think a match like this should be played on Rod Laver Arena maybe. I don't know if the other seeds have good match-ups as well.

"He knows Margaret Court Arena better [and] Melbourne Arena but I haven't thought about it.

"I figured this was always going to be on Rod Laver Arena but I'm ready to go anywhere, whatever it takes."

Trying to banish the memories of last year's shock fourth-round exit, third seed Federer has looked a class above in his two matches so far at Melbourne Park.

The 20-time grand slam champion is eyeing a record-equalling seventh Australian Open title this year.

We take a closer look at Federer's form ahead of his rematch against Australian favourite Millman.

Form and results

While stiffer tests are to come, any slight doubts over Federer and his lack of preparation ahead of the Australian Open have been dismissed. The 38-year-old progressed to the third round at Melbourne Park for the 21st straight year by easing past Filip Krajinovic on Wednesday. Federer tallied 42 winners and just 14 unforced errors.

R1: bt Johnson 6-3 6-2 6-2
R2: bt Krajinovic 6-1 6-4 6-1

Next up

It is a reunion for Federer and Millman, who sensationally eliminated the superstar from the US Open last 16 in 2018. Riding a wave of local support, the 47th-ranked Millman has seen off Ugo Humbert and 31st seed Hubert Hurkacz en route to his first third-round appearance at the Australian Open since 2016.

Draw

Red-hot American Tommy Paul or Marton Fucsovics would be next for Federer, should the Swiss sensation make it through. There has been plenty of buzz and hype surrounding 22-year-old Paul, who is beginning to realise his potential at Melbourne Park.

What he said

"I think the next match is really going to be a test for me because John is going to be there. He's fit like a fiddle. I've lost to him in the past in a best-of-five set match. I almost lost to him in Brisbane, as well, the first time I played against him. He's from this country, so naturally also it's going to be different intensity. I think this is going to be a good test for me."

French qualifier Barrere and US veteran Isner were forced indoors by the adverse weather threat in New Zealand, with the entire Tuesday schedule taking place on inside courts and without spectators.

Despite Isner rifling down 28 aces to move 10 away from becoming the first man to post 14,000 in ATP tour and grand slam events, Barrere stuck with him and pulled off a 6-7 (3-7) 7-6 (7-5) 6-3 victory.

He snatched the only break of the match in game eight of the deciding set, before serving out for victory, with the world number 88 firing down 10 aces himself across the contest.

Argentine seventh seed Sebastian Baez also fell at the last-32 stage, bowing out 7-6 (7-1) 6-1 to American wildcard Ben Shelton.

Serbian Laslo Djere set up a second-round clash with top seed Casper Ruud by edging out Spain's Jaume Munar 3-6 6-1 7-6 (7-4), while Czech Jiri Lehecka will face second seed Cameron Norrie next after sinking Brazilian fellow qualifier Thiago Monteiro 6-3 7-5.

Ruud and Norrie received first-round byes.

At Adelaide International 2, American eighth seed Tommy Paul battled past Australian Christopher O'Connell 6-4 7-5, setting up an appetising second-round clash with Britain's Jack Draper, who won through on Monday.

There was a home success for the Australian crowd to cheer, though, as qualifier John Millman, who beat Roger Federer at the 2018 US Open, this time dug deep for a 4-6 6-3 7-6 (8-6) win against Spain's Albert Ramos-Vinolas.

America's Nakashima – who took Nick Kyrgios to five sets at Wimbledon – was the highest seed in action as things kicked off on Monday, and the difference in the match proved to be his quality ground strokes.

Both players won at least 79 per cent of their successful first serves, but while Thompson's effectiveness dipped to 39 per cent on his second serve, Nakashima's stayed up at 65 per cent, only allowing two break point opportunities all match.

Nakashima will meet John Millman in the next round after Millman defeated fellow Australian Alexei Popyrin 7-6 (7-1) 4-6 6-3.

Popyrin clearly had the serving advantage, winning the ace count 12-to-four, but in a match where each player only one had break of serve each, Millman found the important points when it really mattered.

Japan's Taro Daniel came back from a rough start to handle the challenge of America's Sebastian Korda 1-6 6-1 6-3.

Korda was in total control early, winning 12 of his 13 points on serve (92 per cent) in the opening set, but that number dipped sharply to 37 per cent (13-of-35) as Daniel turned the match on its head and found a way to counterpunch the American.

The last singles contest saw Kwon Soon-woo win a hard-fought clash with Marcos Giron 7-6 (7-3) 4-6 7-5. The match was so closely contested that Kwon won 51 per cent of the total points (104-of-204), while Giron won 49 per cent (100-of-204).

Meanwhile, Kyrgios was the biggest name in action, taking the doubles court in his Australian Open-winning partnership with Thanasi Kokkinakis, defeating Nicolas Mahut and Edouard Roger-Vasselin 7-6 (10-8) 6-3.

Rinderknech, who sits 65th in the world rankings, had not recorded a Tour-level victory before 2021 but has now triumphed 15 times after cruising past Delbonis 6-4 6-4.

The Frenchman will meet eighth seed Dusan Lajovic in the second round in Antwerp, after the Serbian downed Richard Gasquet 7-6 (7-3) 6-1 on Monday.

The other first-round clash in Belgium saw Alexei Popyrin capitulate in the third set as he succumbed to a 4-6 6-3 0-6 defeat against world number 62 Botic van de Zandschulp.

Americans Jenson Brooksby and Brandon Nakashima also booked their places in the main draw. Brooksby defeated Norbert Gombos 6-4 6-2, while Nakashima overcame Pierre-Hugues Herbert 6-2 6-4.

Meanwhile in Russia, Cilic – who has claimed the crown in Moscow twice previously – recovered from a first-set scare in his round-of-32 tie with qualifier Damir Dzumhur, eventually triumphing 6-7 (4-7) 6-1 6-1.

John Millman experienced similar difficulties, with Benjamin Bonzi claiming the first set before the Australian succeeded 6-7 (5-7) 6-4 6-3 to set up a potential second-round match against fifth seed Alexander Bublik.

This has been a tough season for the Australian, who had not managed to wins at the same Tour-level event since the Australian Open until this week.

But a string of impressive results against Fernando Verdasco, Tommy Paul and then Frances Tiafoe secured a final meeting with Mannarino.

The Frenchman's 2020 struggles have been even more stark, taking a 6-14 record to Kazakhstan, and he proved an accommodating opponent for Millman, failing to take his opportunities.

Five break points came and went for Mannarino in the first set before Millman broke at the first attempt to take the opener.

Mannarino then offered little resistance in the second, waiting until the final game to squander his sixth and last chance as Millman claimed a straight-sets win.

Following his success over De Minaur at the Moselle Open last week, Giron beat the world number 26 once more as he battled to a 7-6 (7-5) 7-6 (7-2) victory in two hours. 

The unseeded American, appearing for the first time in Sofia, rallied from a break down in the second set to reach an ATP Tour quarter-final - where he will meet John Millman - for the fourth time this season. 

Millman, who is seeded eighth, lost the first set against qualifier Illya Marchenko but recovered well to comfortably triumph 5-7 7-6 (7-0) 6-3. 

However, it was far more straightforward for the other favourites, with top seed Jannik Sinner avoiding a second-set blip to defeat Egor Gerasimov 6-2 7-6 (7-3) and Gael Monfils getting a walkover against Ilya Ivashka. 

Number five seed Filip Krajinovic coasted past fellow Serbian Laslo Djere 6-3 6-0 in just over an hour to set up a quarter-final tie with Kamil Majchrzak. 

In Thursday's other match, world number 56 James Duckworth smashed Benoit Paire 6-4 6-4 in just an hour and 15 minutes to collect his 11th win in his past 12 outings. 

Duckworth, who reached his first ATP Tour final in Nur-Sultan last week, will now challenge defending champion Sinner in the next round. 

The Belarusian saw off Aljaz Bedene, with a 6-4 7-6 (7-4) win carrying him through to the quarter-finals of the Open Sud de France.

Bedene was British number two to Murray heading into Wimbledon in 2016, when the Scot won his third grand slam title, but has since reverted to representing his native Slovenia.

He put up a fight against Gerasimov, who sank Murray in straight sets on Tuesday, but the 28-year-old from Minsk took three of his five break-point opportunities and held his nerve in the tie-break to advance.

The success for Gerasimov sets up a last-eight clash with Spain's Alejandro Davidovich Fokina, who scored a fine 7-5 6-2 win over Polish fourth seed Hubert Hurkacz.

Top seed and world number 13 Roberto Bautista Agut raced to a 6-0 6-3 victory over French qualifier Gregoire Barrere, but Croatian third seed Dusan Lajovic tumbled out, losing to Dennis Novak in straight sets.

At the Singapore Open, second seed John Millman fell by the wayside, the Australian slumping 6-4 6-1 to compatriot Matthew Ebden.

French top seed Adrian Mannarino encountered no such problems, ending the hopes of Roberto Marcora with a 6-3 7-5 win to join Ebden in the quarter-finals.

Zverev was crowned Cologne Indoors champion last weekend and the US Open runner-up moved into the quarter-finals of the Cologne Championships on Wednesday.

The top seed beat Australian Millman 6-0 3-6 6-3, despite double-faulting 10 times, and has now won 11 of his last 12 matches on hard courts.

Zverev saved six of the seven break points Millman earned and won 79 per cent of points behind his first serve, setting up a last-eight meeting with eighth seed Adrian Mannarino.

Mannarino was a 6-3 6-3 winner against Miomir Kecmanovic, while Alejandro Davidovich Fokina advanced to the quarter-finals following a 7-6 (7-3) 6-3 victory over Steve Johnson.

Felix Auger-Aliassime, beaten by Zverev in the final on Sunday, rallied past qualifier Egor Gerasimov 4-6 7-6 (7-2) 7-6 (7-4).

Pablo Carreno Busta slumped to a surprise defeat at the European Open in Antwerp, Ugo Humbert beating the second seed 5-7 6-3 6-4.

Frenchman Humbert was joined in the quarter-finals by Grigor Dimitrov, Alex De Minaur and Dan Evans, while Milos Raonic and Taylor Fritz progressed to the round of 16.

World number one Medvedev fought back from a set down to defeat Aslan Karatsev 3-6 6-4 6-2 and advance to a quarter-final against fifth seed Roberto Bautista Agut, who was granted a walkover after Nick Kyrgios pulled out with an abdominal issue. 

The Russian got just 48 per cent of his first serves in during a blustery opening set before improving to 68 per cent in the second and controlling the decider as Karatsev struggled with injury. 

"It was tough to play [in] rhythm. It felt like many points were just whoever managed to put the ball in the court was going to win the point," Medvedev said of the tricky conditions. 

"It was not easy but I'm happy to win because that's the most important [thing]. 

"Last year was amazing. I played great tennis. Hopefully I can do the same this year. I like it here in Mallorca, so hopefully I can stay as long as possible in the tournament." 

Alongside Medvedev and Bautista Agut, Stefanos Tsitsipas is the only other seed left in the draw after he overcame Ilya Ivashka 6-4 6-4. 

Denis Shapovalov was a 6-4 6-1 loser against Benjamin Bonzi, Pablo Carreno Busta went down 6-3 6-4 to Antoine Bellier and Sebastian Baez's meeting with Daniel Altmaier ended in a 6-2 2-6 6-4 defeat for the Argentine. 

At the Eastbourne International, second seed Sinner suffered a 6-3 3-6 6-3 loss to Tommy Paul as he made his return from a knee injury sustained at the French Open.

World number 13 Sinner remains without a grass-court win in his ATP Tour career, while Paul will next face defending champion Alex de Minaur, who overcame Lorenzo Sonego 7-6 (7-3) 6-2 in a repeat of last year's final. 

Jack Draper defeated fourth seed Diego Schwartzman 7-5 7-6 (7-3) to advance to the quarter-finals and Cameron Norrie cruised past Brandon Nakashima in straight sets.

There were also wins for Maxime Cressy, Alexander Bublik and Taylor Fritz. 

Eighth seed Millman was made to work exceedingly hard to avoid an early exit, eventually coming through a contest in which the two Australians faced a combined 31 break points by a 7-6 (7-3) 3-6 7-5 scoreline.

Ricardas Berankis won a 22-point tie-break in the first set to defeat Maximilian Marterer, while there were also wins for Millman's next opponent Guido Pella, Federico Coria and Ilya Ivashka.

At the Estoril Open, Kevin Anderson saved a match point at 6-5 down in the second set tie-break and turned around a 4-1 deficit in the third set to beat Frances Tiafoe 4-6 7-6 (8-6) 7-6 (7-4).

"It was obviously a very, very close match," Anderson said. "I think there were a lot of positives, a lot of really high-quality tennis, especially from midway through the second until the end of the match, I was really happy with the way I played.

"I think even if I had lost that match, obviously it's always tough losing, but I definitely felt I took a step in the right direction.

"Getting the win is a big added bonus, it gives me another opportunity to come out in a couple days' time."

Eighth seed Alejandro Davidovich Fokina beat Pablo Andujar in three sets, with Jeremy Chardy and qualifier Nuno Borges also victorious in Portugal.

Murray chose to play in the event as a wildcard to improve his world ranking and avoid tougher first-round encounters, such as facing Stefanos Tsitsipas at the U.S. Open, and he recovered from going behind in the opening set to ease through his first-round tie.

Humbert, who is ranked 26th in the world, came into the clash 87 places ahead of the two-time Wimbledon winner but failed to make home advantage count as the Scot dispatched of him in just over two hours.

Karen Khachanov, who is the seventh seed in Metz, avoided a similar first-set scare to overcome Alexandre Muller 4-6 6-1 6-3, while Marcos Giron edged past Arthur Rinderknech 3-6 7-6 (7-3) 6-4.

That win sets up a second-round tie with fourth seed Alex de Minaur, with Alejandro Davidovich Fokina sneaking past Gilles Simon 4-6 (4-7) 7-6 (7-2) 6-2 in Tuesday's other match.

Frenchman Benoit Paire crashed out of the Astana Open to world number 97 Egor Gerasimov as he lost 7-5 6-4.

John Millman, the fifth seed, did not endure similar struggles as he recovered from losing the first set to ease past Dmitry Popko 3-6 6-1 6-4.

Meanwhile, Ilya Ivashka coasted past Elias Ymer 6-2 6-4 in just over 90 minutes to secure his second-round berth in the Czech Republic.

Murray, who had not played at Indian Wells in four years, won in one hour and 24 minutes with a disciplined display, winning 82 per cent of first serve points.

The Briton, who only faced one break point for the match, will next take on Spanish 18-year-old Carlos Alcaraz, who enjoyed a fine run to the US Open quarter-finals in September.

"I think Alcaraz is really, really good," Murray said after the win. "I think he’s got a good chance at it."

On his own performance, Murray added: "I thought my mentality was good tonight. I sort of focused just on every single point.

"It's been a tough road to get back and it was so nice that so many people managed to come out and support today. I really enjoyed it."

BROOKSBY SETS UP ZVEREV DATE

Emerging American Jenson Brooksby triumphed over Cem Ilkel 7-6 (7-5) 6-4 to book his spot in the second round where he will face third seed Alexander Zverev.

The 20-year-old world number 79, who was the runner-up at the Hall of Fame Open in July, prevailed in his Indian Wells debut in one hour and 44 minutes.

Brooksby dropped only four points on his serve, with Ilkel unable to generate a break point throughout the match.

The California native has been a break-out star in the latter half of 2021, reaching the fourth round at the US Open, entering the top 100 after starting the year ranked 307th.

SOCK PUT AWAY BY AUSTRALIAN

Former top 10 player Jack Sock was bundled out by Australian John Millman 7-5 4-6 6-3 in an epic first-round clash which lasted two and a half hours.

Sock, who has battled injuries in recent times and was handed a wild card for Indian Wells, pushed Millman all the way, with the Australian breaking to lead 5-3 in the third set before serving out for victory.

World number 61 Pedro Martinez made light work of Italian qualifier Roberto Marcora 6-4 6-0 to set up a second-round meeting with second seed Stefanos Tsitsipas. The 24-year-old Spaniard triumphed in one hour and 15 minutes.

Former Wimbledon and US Open finalist Kevin Anderson sent down 10 aces in a 7-5 6-2 win over Jordan Thompson.

In his opening ATP Tour match of the year, three-time grand slam winner Murray slipped up 6-3 5-7 6-3 against Bagnis, a player who began the year with a 30-59 win-loss career record.

Left-hander Bagnis rose to the occasion on Rod Laver Arena to earn the scalp of the former world number one.

Murray, down at 134th in the rankings after another injury-hit year, is looking to make headway on that front in 2022 under new coach Jan de Witt, so that he can avoid having to take wildcards into tournaments.

He was allowed into this tournament by that back-door route, and has also been confirmed for an Australian Open wildcard, but the Scot could not find the form that saw him beat Rafael Nadal at an exhibition event in Abu Dhabi in late December.

Bagnis said of his win: "In the beginning it was a pleasure to play against Andy and right now to beat him is amazing. I'm really happy."

He added, according to the tournament website: "Yesterday, I came to see the stadium, to see it all around because the atmosphere is different when you play on any court outside… I enjoyed it a lot. It was so good for me."

Nadal was also back in action on Tuesday, playing his first match on the main tour since August as he teamed up with fellow Spaniard Jaume Munar for a doubles win.

A foot injury meant Nadal's 2021 season ended early, but he warmed up for singles tests that lie ahead by joining Munar for a 6-3 3-6 10-4 win over Argentinians Sebastian Baez and Tomas Martin Etcheverry.

At the Adelaide International 1 tournament, there was a notable first-round win on Tuesday for Australian Thanasi Kokkinakis, who saw off compatriot John Millman 6-4 6-3.

Kokkinakis, a major talent as a youngster, is battling to reassert himself on tour after injury troubles, and beating Millman put his name up in lights for at least one day.

He reflected afterwards on the battle it has taken so far, with last year spent largely living out of a suitcase on the second-tier Challenger Tour.

"It was a gruelling year travelling," said Kokkinakis. "I've played a couple of times [in Adelaide] but just in exhibitions, so to play a real meaningful tournament and beat such a quality opponent, a proven veteran like Johnny, means a lot. I played great, and the support was great, so I'm really happy."

Coming off an epic three-hour duel Wednesday in his first match since the French Open final, Nadal fell to Lloyd Harris 6-4 1-6 6-4 on Thursday at the Citi Open. 

After a short-lived maiden appearance at the Washington, D.C. tournament, the Spaniard will look ahead to Toronto and Cincinnati as he continues his preparations for the U.S. Open. 

Harris, meanwhile, heads to a quarter-final matchup against veteran Kei Nishikori after recording the biggest win of his career. 

Facing Nadal for the first time, the 24-year-old South African slammed 16 aces Thursday and saved four of six break points. 

The 20-time grand slam winner, who battled a foot injury to outlast Jack Sock in his first match, did not have enough to answer the world number 50 on Thursday.

In addition to the top-seeded Nadal's defeat, second seed Felix Auger-Aliassime also went down Thursday, falling 6-3 6-4 to American wild card Jenson Brooksby. 

With their exits, the tournament is now without its top four seeds. 

That leaves fifth seed Jannik Sinner as the top player remaining after he defeated Sebastian Korda 7-6 (7-3) 7-6 (7-3). 

Nishikori advanced by downing seventh seed Cameron Norrie 3-6 6-3 6-3, while John Millman knocked out eighth seed Reilly Opelka 6-3 7-6 (7-4). 

Among unseeded players, Denis Kudla defeated the red-hot Brandon Nakashima 3-6 7-6 (7-3) 6-4, while Steve Johnston eased past Ricardas Berankis 6-2 6-1 and Mackenzie McDonald beat Illya Ivashka 6-4 6-4. 

In addition to Harris-Nishikori, Kudla will face McDonald in the other quarter-final in the top half of the draw, while Sinner meets Johnson and Millman takes on Brooksby in the bottom half. 

Handed a bye for the opening round, third seed Khachanov made home advantage count in his first match as the Russian defeated Australian world number 50 James Duckworth 3-6 6-3 6-1 to reach the quarter-finals on Wednesday.

Khachanov – Olympic Games silver medallist, who triumphed in Moscow three years ago – will face another Australian, John Millman after he defeated Illya Marchenko 6-1 5-7 6-4 at the ATP 250 tournament.

"It always feel great to be back in your hometown, in a tournament where everything started for me as a professional tennis player," world number 31 Khachanov said.

"[This is] where I won my first matches, I got my first points. Since then, it's always great to come back home to see a crowd, [get] home support. It's also little bit more nervous, of course. But I always enjoy playing at home."

Khachanov was joined in going through to the last eight by sixth seed Marin Cilic – a two-time Kremlin Cup champion who overcame Tommy Paul 7-5 6-3.

At the European Open in Antwerp, top seed Jannik Sinner downed fellow Italian youngster Lorenzo Musetti 7-5 6-2 in the duo's first meeting as professionals.

"We never practice together, so it was kind of a new match," Sinner said post-match.

"He's an incredible player. He's a very great talent, so I hope we will have a couple of more matches on the pro tour, and obviously I'm very happy about my level today."

Arthur Rinderknech upstaged eighth seed Dusan Lajovic 6-3 4-6 6-2 to set up a quarter-final tie with Sinner, who is in the hunt for a fourth title of the season and a place at next month's ATP Finals in Turin.

Another emerging talent, qualifier Jenson Brooksby, bettered US Open quarter-finalist Botic van de Zandschulp 6-2 6-0, with Alejandro Davidovich Fokina sending third seed Cristian Garin packing 4-6 6-3 6-3.

Nishikori trailed 6-4 4-2 and was forced to break serve as Guido Pella attempted to close out the match in the second set, before sensationally rallying to a 4-6 7-6 (7-4) 6-2 win on Monday.

A two-time champion at the ATP 500 tournament on the Barcelona clay, Nishikori broke serve on three occasions in the final set en route to the second round.

"He had the match today at 6-5, serving [for the match]," said Nishikori. "He was much better in the first and second [sets] and 3-0 up in the tie-break. I don't know how I fought through. [In the] third set, I was playing much better.

"I was making so many unforced errors in the first and second [sets]. Maybe he got a little bit tired and I was playing strong in the third set. I want to take that to the next round… The way I fought today and the way I played in the third set was good."

Next up for 2014 US Open finalist Nishikori is 13th seed Cristian Garin.

Ilya Ivashka topped Tallon Griekspoor 6-3 6-1 and the qualifier's reward is a showdown with top seed and 20-time grand slam champion Rafael Nadal.

Cameron Norrie, Pablo Andujar, Jeremy Chardy, Pierre-Hugues Herbert, Jaume Munar, Federico Gaio, Egor Gerasimov and Bernabe Zapata Miralles all advanced to the last 32.

At the Serbia Open, seeds Filip Krajinovic and John Millman booked their spots in the round of 16.

With the ATP 250 tournament being staged for the first time since 2012 and headlined by world number one Novak Djokovic, Serbian fifth seed Krajinovic overcame Stefano Travaglia 7-5 5-7 6-3 in a Belgrade rollercoaster.

Millman – the Australian seventh seed – took down local wildcard Danilo Petrovic 7-5 6-4 as Marco Cecchinato and Nikola Milojevic won through.

By far the most experienced player remaining in the field after Harris' upset of Rafael Nadal on Thursday, Nishikori prevailed 6-3 7-5 to avenge a loss earlier this year in their only prior meeting. 

Nishikori had lost his last six ATP quarter-final matches dating to a trip to the semis in Barcelona in April 2019. 

The 31-year-old next faces Mackenzie McDonald, who downed countryman Denis Kudla 6-3 6-2 to reach his second career ATP semi-final. He has never played in a final. 

In the other semi-final, fifth seed Jannik Sinner will meet wild card Jenson Brooksby. 

Sinner had little trouble with American veteran Steve Johnson in a 6-4 6-2 win as the Italian won 93 per cent of his first-serve points and saved all three break points he faced. 

Brooksby maintained the strong return game that as carried him all week in a 6-1 6-2 upset of 11th seed John Millman. 

The Australian did not manage an ace against the 20-year-old American, who won 54 per cent of the points on Millman's serve and converted five of seven break points. 

At 130 in the world, Brooksby is the lowest-seeded Citi Open semi-finalist since John Isner reached the 2007 final while ranked 416th.